<template>
  <view>
    <view class="scroll-view-container">
      <!--  左侧滑动-->
      <scroll-view class="left-scroll-view" scroll-y :style="{ height: wh + 'px' }">
        <block v-for="(item, index) in cateList" :key="index">
          <view :class="['left-scroll-view-item', index === active ? 'active' : '']" @click="activeChanged(index)">{{ item.cat_name }}</view>
        </block>
      </scroll-view>
      <!--  右侧滑动-->
      <scroll-view scroll-y="true" :style="{ height: wh + 'px' }" :scroll-top="scrollTop">
        <!-- 动态渲染二级分类的列表数据 -->
        <view class="cate-lv2" v-for="(item2, index) in cateLevel2" :key="index" @click="goCoodsList(item2)">
          <view class="cate-lv2-title">{{ item2.cat_name }}</view>
          <!-- 动态渲染三级分类的列表数据 -->
          <view class="cate-lv3-list">
            <!-- 三级分类 -->
            <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3">
              <image :src="item3.cat_icon"></image>
              <text>{{ item3.cat_name }}</text>
            </view>
          </view>
        </view>
      </scroll-view>
    </view>
  </view>
</template>

<script>
export default {
  data() {
    return {
      wh: 0, // 窗口高度
      cateList: [], // 分类数据列表
      active: 0, // 激活class
      cateLevel2: [], // 二级分类列表
      scrollTop: 0
    };
  },
  onLoad() {
    // 获取当前系统的信息
    const sysInfo = uni.getSystemInfoSync();
    // 为 wh 窗口可用高度动态赋值
    this.wh = sysInfo.windowHeight;
    this.getCateList();
  },
  methods: {
    goCoodsList(item2) {
      uni.navigateTo({
        url: '/subpkg/goods_list/goods_list?cid=' + item2.cat_id
      });
    },
    activeChanged(index) {
      this.active = index;
      // 赋值二级分类
      this.cateLevel2 = this.cateList[index].children;
      this.scrollTop = this.scrollTop === 0 ? 1 : 0;
    },
    async getCateList() {
      const { data } = await uni.$http.get('/api/public/v1/categories');
      if (data.meta.status !== 200) return uni.$showMsg();
      // 赋值二级分类
      this.cateLevel2 = data.message[0].children;
      this.cateList = data.message;
    }
  }
};
</script>

<style lang="scss">
.scroll-view-container {
  display: flex;
  .left-scroll-view {
    width: 120px;
    .left-scroll-view-item {
      line-height: 60px;
      background-color: #f7f7f7;
      text-align: center;
      font-size: 12px;
      // 激活项的样式
      &.active {
        background-color: #ffffff;
        position: relative;
        // 渲染激活项左侧的红色指示边线
        &::before {
          content: ' ';
          display: block;
          width: 3px;
          height: 30px;
          background-color: #c00000;
          position: absolute;
          left: 0;
          top: 50%;
          transform: translateY(-50%);
        }
      }
    }
  }
  .cate-lv2-title {
    font-size: 12px;
    font-weight: bold;
    text-align: center;
    padding: 15px 0;
  }
  .cate-lv3-list {
    display: flex;
    flex-wrap: wrap;
    .cate-lv3-item {
      width: 33.3%;
      display: flex;
      flex-direction: column;
      align-items: center;
      margin-bottom: 10px;
      image {
        width: 60px;
        height: 60px;
      }
      text {
        font-size: 12px;
      }
    }
  }
}
</style>
